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 Betreff des Beitrags: Grundig TK54
BeitragVerfasst: Do Mär 05, 2020 15:26 
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Registriert: Do Nov 10, 2016 20:31
Beiträge: 17
Kenntnisstand: Spezialkentnnisse im Bereich Röhrenradios (Beruf)
I have a Grundig TK54 that I am restoring. I am replacing capacitors and have a question about these two large electrolytic capacitors. They are the motor caps. Can I replace them with normal electrolytic capacitors or do I need special ones? Thanks for any advice.


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 Betreff des Beitrags: Re: Grundig TK54
BeitragVerfasst: Do Mär 05, 2020 15:55 
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Registriert: Di Apr 19, 2016 20:33
Beiträge: 795
Kenntnisstand: Elektrotechnischer Beruf/ Studium
Hello John,

these are NOT electrolytic capacitors. Motor Caps ALWAYS, in 1959 as well as in 2020, are Metal-Paper-Capacitors. (Mind the MP letters upon them). Metal-Paper-Caps for ac motor operation are common at electric supply dealers everywhere. Larger ones for your washing mashine, smaller ones for your Grundig.

Both the right capacity and ac voltage are important. For 4,3µF, you can use 4,5µ, for 1,5µ, if not available (but I think they are) just combine 1,0 and 0,5 (0,47µ) in parallel.
On the left one on your pic, 220V~ DB means 220 V AC with permanent operation
and (unreadable) V~ AB means xxx V AC within 25 % of operation time. Obviously, the cap sees more voltage when rewinding the reels. So take a new one with the higher of the two Voltage values.

Don't try to use electrolytics. They will explode when connected to ac power. Electrolytics ALWAYS stand only DC.

Off topic: Keep in mind that the TK 54 can play back four track stereo tapes. It will record only in mono. It comes from the era where pre-recorded stereo tapes were on sale, but radio broascasts (most common recording source) still in mono.

BR, Stefan


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 Betreff des Beitrags: Re: Grundig TK54
BeitragVerfasst: Do Mär 05, 2020 16:52 
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Thank you Stefan: Very useful information. I am in Canada so the AC operation is 120V. I will try to find the right caps. I believe the higher capacitance unit is the start capacitor. Would the capacitors in this link be suitable for replacement? Can I use them for both the run and start capacitor? https://www.ebay.ca/itm/CBB61-450VAC-1- ... lRpvPP1g3A Thanks


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 Betreff des Beitrags: Re: Grundig TK54
BeitragVerfasst: Fr Mär 06, 2020 10:09 
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Registriert: Di Apr 19, 2016 20:33
Beiträge: 795
Kenntnisstand: Elektrotechnischer Beruf/ Studium
Be careful, John:
The actual line voltage is not relevant, the motor runs over the mains transformer and gets always the same voltage, no matter if ac in put is 120 or 220 or whatever. So you must get the (at least) same voltage ratings as the original caps show.

(I assume you have the TK 54 "U" version for North America, including 60 cps AC. The german modell has other Cap values.)

There is no start capacitor, both are operation or "Run" capacitors. There are two pieces because the motor has seperate coils for two running speeds: A high speed for 3 3/4 and 7,5 ips (selected mechanically by switching the belt wheel), the other, low speed is switched electrically and use with 1 7/8 ips (with mechanical (belt) setting like in 9,5 position)

I am not quite sure if the caps in your ebay link will do the job, for there are specified as start caps. Motor Run Capacitors are usually larger and come in a tin can, like these (don't mind the value, just example): https://www.ebay.ca/itm/AC-Motor-Run-Ca ... SwanFctkYC

Maybe you should ask an electricy engineer in your region - or you use those in your link- and see if they will last. To be honest, this is the way I would probably take - trial and error :)

Stefan


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 Betreff des Beitrags: Re: Grundig TK54
BeitragVerfasst: Fr Mär 06, 2020 16:17 
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Registriert: Do Nov 10, 2016 20:31
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Kenntnisstand: Spezialkentnnisse im Bereich Röhrenradios (Beruf)
Thanks Stefan. This is the first Tape machine I have worked on and the service manual is in German. So, the technical information on its electrical construction is difficult to translate. My feeling is that the caps I linked to are rated at 450V AC so they should work . Anyway, the motor is running fine now so I will use the original capacitors until I notice problems with the motor speed.


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 Betreff des Beitrags: Re: Grundig TK54
BeitragVerfasst: So Mär 08, 2020 12:14 
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Registriert: Di Apr 19, 2016 20:33
Beiträge: 795
Kenntnisstand: Elektrotechnischer Beruf/ Studium
So you only wanted to replace them although their aren't defective?? In fact I already wondered about them, cause I saw defecte motor run caps in old Grundigs (at least 100 pieces) exactly once in my life.
Haha, i tell you something, without knowing how old you are, I predict they will last longer then your remaining lifetime... :-)

You have the complete German Service Manual? If not, tell me your email address, not here, but in a personal message and I'll send you a pdf, plus, an english serv. manual of TK54's half-track brother TK 35.

Stefan


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